Water contains dissolved natural organic material (NOM) derived from environmental processes such as soil formation and erosion, biological productivity, and plant decomposition -- all of which occur to varying extents in the catchments, rivers, reservoirs, lakes, and aquifers of a watershed. When water is processed for potable use, it is treated with disinfectants such as chlorine for pathogen control. Unfortunately, disinfectants react with NOM to form undesirable halogenated chemical byproducts. Several of these byproducts have been linked through epidemiological studies to increased occurrence of bladder cancer, miscarriages, and leukemia. Our studies address the propensity of source waters to form two of these byproducts, trihalomethanes and haloacetic acids, that are regulated in drinking water by the U.S. Environmental Protection Agency. We will present data from California and national water supplies that demonstrates the propensity of NOM to form byproducts varies with watershed characteristics such as seasonal river discharge cycles, land-use practices in the catchment, and the types of soils and plants present. With this data we will also demonstrate that the models for predicting byproduct formation from NOM (those used to design current drinking water regulations) do not reproduce observed variations in byproduct formation. The results indicate that the current understanding of byproduct formation does not reflect real-world conditions, and demonstrate the utility of considering watershed characteristics in assessing the source-specific contribution of natural organic matter to byproduct formation. See water.wr.usgs.gov
Learning Objectives: N/A
Keywords: Drinking Water Quality, Environment
Presenting author's disclosure statement:
Organization/institution whose products or services will be discussed: None
I do not have any significant financial interest/arrangement or affiliation with any organization/institution whose products or services are being discussed in this session.